Telerik ASP.NET Ajax client-side framework failed to load

Telerik;0x800a139e - JavaScript runtime error: ASP.NET Ajax client-side framework failed to load;0x800a1391 - JavaScript runtime error: 'Sys' is undefined

For Internet Explorer users getting the following error:

Problem:

Recently I encountered an issue, RadScriptManager started throwing the following errors:

0x800a139e - JavaScript runtime error: ASP.NET Ajax client-side framework failed to load.

0x800a1391 - JavaScript runtime error: 'Sys' is undefined

This issue is observed on IE 11 and doesn't appear on Chrome or Firefox Browsers.

Suggested solution:

I had below in my web.config. I removed runtimeversion2.0 and it worked well.

<add name="Telerik_Web_UI_WebResource_axd" path="Telerik.Web.UI.WebResource.axd"
                 type="Telerik.Web.UI.WebResource" verb="*"
                 preCondition="integratedMode,runtimeVersionv2.0"/>